SDA is now a part of Bay Alarm Company. Founded by the Westphal family in 1946 and a 30-year partner of SDA Security, Bay Alarm remains a family owned and operated California Alarm Company. Protecting over 120,000 California families and businesses, Bay Alarm is committed to carrying on the personal service only a family run business can deliver. Bay Alarm is proud to welcome all SDA Security customers to our family.